Millions of tons of nitrogen oxides, (denoted, generally herein as "NO.sub.x "), are emitted into the atmosphere each year as a result of high temperature combustion of fossil fuels. Nitrogen oxides have been cited as major contributors to acid rain, by some estimates being about one-third of the acid contribution. Thus global interest has been focused on development of practical apparatus and methods to reduce the entry of nitrogen oxides into the atmosphere.
Since the first part of this century, developmental efforts have been directed to convert nitrogen oxides to the individual elemental diatoms, N.sub.2 and O.sub.2. Yet despite the lengthy search, no previous investigator has succeeded in devising a large scale procedure that does not require introduction of an exogenous reducing agent such as NH.sub.3, CH.sub.4, or CO. Alternatively, the use of electron beam (e-beam) irradiation, electrical discharge irradiation, and light (laser or flash) has been unsuccessfully attempted.
Previous investigation on chemical reactions in electrical discharge includes the work of Joshi in the 1920s (NO.sub.2 and N.sub.2 O decomposition/electron movement between glass walls in AC discharge), Visvanathan in the 1950s (NO decomposition in electric charge). Others looking at the general conditions of electric/chemical reactions include Brewer and Westhaver (J. of Phys. Chem.; 33:883 (1929)), Lacoste, G. and Bess, R (Rev. Chim. Minerale; 11:14 (1974)), Bess, R. (Rev. Phys. Appl.; 12:1029 (1977)). A more comprehensive presentation of the previous work in nitrogen oxide control is presented in A Unified Projection of the Performance and Economics of Radiation-Initiated NO.sub.x /SO.sub.x Emission Control Technologies, Person et al. Dept. of Energy Contract No. DE-AC22-84PC70259 (1985), the teachings of which are incorporated herein by reference. Particular note is made of the following, "An Advanced Corona Discharge NOx Control System," Ronald W. Breault, Frederick E. Becker, V. K. Mathur, Christopher McLarnon, Jeff Chini, AlChE Spring National Meeting, Session 99: Contaminants Removal From Gas II, New Orleans, La. (1992); "Reaction Gas Kinetics for Flue Gas, Gas Treatment of NOx", Ronald W. Breault, Christopher McLarnon, V. K. Mathur, NATO Advanced Research Workshop on Non-Thermal Plasma Techniques for Pollution Control (Cambridge University, England, Sep. 21-25, 1992); "The Tecolytic.TM. Process. An Advanced NOx Control System", Ronald W. Breault, V. K. Mathur, Christopher McLarnon, Jeff Chini, International Gas Research Conference (Orlando Fla., Nov. 16-19, 1992), the teachings of which are incorporated herein by reference.
Other works on electro-catalysts take a position directly opposite from the instant invention. Such are those of van den Bleek, et al., (I. Chem. E. Symposium Series, U. of Salford (1979)) stating that efficiency of nitrogen oxide reduction is improved when catalytic surfaces are able to donate an electron to the oxide, and Wooten and Mangold (U.S. Pat. No. 3,562,127 (1971)) (using gold plated, i.e. conductive, metal wool) and reporting augmented nitrogen reduction only when gold is used.
The instant inventive apparatus and method overcomes the problems previously encountered in the art. This invention employs a novel concept based on recognizing chemical reactions occurring in gaseous electrical discharge as distinct from reactions that result when equally energetic electrons are made to travel on metal surfaces.